Associated Companies Tax Calculator
Calculate how associated companies affect your Corporation Tax thresholds and marginal relief. See the impact of shared profit bands on your company's tax bill.
Excluding your company. Enter 0 if no associated companies.
What are associated companies?
Companies are associated if one controls the other, or both are under common control. This includes control by the same person(s) or connected persons. Associated companies share Corporation Tax thresholds, reducing the profit band available to each company.
How do associated companies affect Corporation Tax?
The upper and lower Corporation Tax thresholds (£250,000 and £50,000) are divided by the number of associated companies plus one. With one associated company, thresholds become £125,000 and £25,000 per company.
Do dormant companies count as associated?
Dormant companies (those not carrying on business or trade) are generally not counted as associated companies for Corporation Tax threshold purposes, provided they have no income or gains.
What is marginal relief for Corporation Tax?
Marginal relief applies when profits fall between the lower and upper thresholds (£50,000-£250,000 for single companies). It provides a gradual increase in effective tax rate between 19% and 25%, calculated using the marginal relief fraction.
How do I count associated companies?
Count all companies under common control at any point in the accounting period. Include overseas companies but exclude dormant companies. The count determines how thresholds are divided for marginal relief calculations.
Multiple Companies?
Consider company structure carefully. Associated companies share CT thresholds, potentially increasing your overall tax burden.